1. Field of the Invention
The continuing expansion of new tools, protocols, techniques, and reagents has allowed molecular biologists and immunologists to ask novel questions concerning obscure physiological processes and, in many situations, obtain some insight into the components of the process and the manner in which the components operate. Important to the existence of all vertebrates is their ability to defend themselves against pathogens. In mammals, the immune system is divided into a number of different pathways, each pathway having different defense mechanisms, different components, and different modes of regulation.
The killer cells, of which there are many subsets, are able in a restricted or unrestricted manner to kill cells which can be distinguished from normal cells of the host. These cells may arise from viral transfection or transduction, neoplastic transformation, or transplantation from an allogeneic host, where the transplanted tissue or organ has one or more different major histocompatibility (MHC) Class I or minor histocompatibility surface antigens from the host.
There is substantial interest in being able to understand and influence the natural physiological processes. In the case of transplantation, the ability to inhibit graft rejection would greatly increase the success of the transplantation and possibly allow for broader disparity between the MHC antigens of the donor and the recipient. Understanding of the processes by which killer cells select and destroy other cells will aid in an understanding of autoimmune diseases, as well as allow for aiding individuals who are deficient in their immune response.
It is therefore of substantial interest to be able to identify the structural genes, the regulatory regions associated with the structural genes, and the expression products of the structural genes associated with the various immune mechanisms, particularly in humans. One avenue which would have significant beneficial effect in diagnosis and therapy would be the availability of the genes and components of the killer cell lytic process.
2. Description of the Relevant Literature
Polypeptides released from killer cells and their cytoplasic granules have been implicated in the lytic event of killer cell lysis mechanisms, such polypeptides including serine proteases, toxic lymphokines and pore forming poly-perforins. (Henkart, et al., J. Exp. Med. (1984) 160:75; Podack and Konigsberg, ibid (1984) 160:695; Podack, Immunology Today (1985) 6:21; Henkart, Ann. Rev. Immunol. (1985) 3:31; Martz, Immunology Today (1984) 5(9):254.) The inhibition of CTL or NK mediated target cell lysis by low and high molecular weight serine protease inhibitors has been demonstrated. (Wright and Bonavida in Natural Killer Activity and Its Regulation (Ed. T. Hoshinu, et al.) Excerpta Medica, Amsterdam, p. 145 (1984) and references cited therein). Hatcher, J. Immunol. (1978) 120:665 isolated a cytotoxic serine protease from unstimulated human peripheral blood lymphocytes with an approximate molecular weight of 30 kB. Pasternak and Eisen, Nature (Lond.) (1985) 314:743, reported a tryspin-like serine protease of 28 kD specific for CTL cells. Marks, Science (1986) 231:1367 describes general theories concerning cell mediated cytoxicity. See also U.S. patent application Ser. No. 860,085, filed May 6, 1986, which reports a murine killer cell protease.